Chemical Reactions and Equilibrium: Interactive Quizzes for Year 12 Chemistry

Question 1

The half-life of a radioactive isotope is 50 days. After 150 days, what fraction of the original radioactive isotope remains?

Accepted Answer

1/8

Answer

1/2

Answer

1/4

Answer

1/16

Question 2

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

A catalyst lowers the activation energy of a reaction

Answer

A catalyst increases the activation energy of a reaction

Answer

A catalyst provides an alternative pathway for a reaction

Answer

A catalyst is consumed in the reaction

Question 3

Define reaction order succinctly, highlighting its significance in understanding the kinetics of chemical reactions.

Accepted Answer

Reaction order is an exponent in a mathematical equation that describes the relationship between reactant concentrations and reaction rates.

Answer

Reaction order represents the number of molecules involved in a reaction.

Answer

Reaction order indicates the rate at which reactants are consumed.

Answer

Reaction order remains constant throughout a reaction.

Question 4

True or False: The equilibrium constant for a reaction is a measure of the relative amounts of reactants and products at equilibrium.

Accepted Answer

True

Answer

False

Question 5

Which factor does NOT influence the rate of a chemical reaction?

Accepted Answer

Volume of the reaction vessel

Answer

Temperature

Answer

Concentration of reactants

Answer

Surface area of solids (for reactions involving solids)

Question 6

Which of the following is an example of a homogeneous reaction?

Accepted Answer

Reaction between hydrogen and oxygen gases

Answer

Reaction between sodium and hydrochloric acid solution

Answer

Reaction between solid copper and silver nitrate solution

Answer

Reaction between solid sodium chloride and solid silver nitrate

Question 7

The Haber process is primarily used to produce:

Accepted Answer

Ammonia

Answer

Nitric acid

Answer

Sulphuric acid

Answer

Hydrochloric acid

Question 8

Which of the following is considered a weak acid?

Accepted Answer

Acetic acid

Answer

Hydrochloric acid

Answer

Sulphuric acid

Answer

Nitric acid

Question 9

Which of the following is an example of a homogeneous equilibrium?

Accepted Answer

Liquid H2O(l) ⇌ H+(aq) + OH-(aq)

Answer

Solid CaCO3(s) ⇌ CaO(s) + CO2(g)

Answer

Solid NaCl(s) ⇌ Na+(aq) + Cl-(aq)

Answer

Solid AgCl(s) ⇌ Ag+(aq) + Cl-(aq)

Question 10

What is the conjugate acid of NH3?

Accepted Answer

NH4+

Answer

OH-

Answer

H2O

Answer

H+

Question 11

Which of the following parameters does NOT influence the rate of a chemical reaction?

Accepted Answer

Volume of the reaction container

Answer

Temperature

Answer

Concentration of reactants

Answer

Surface area of reactants

Question 12

A reaction has a half-life of 10 minutes. If the initial concentration of the reactant is 1.0 M, what will be the concentration after 20 minutes?

Accepted Answer

0.125 M

Answer

0.25 M

Answer

0.5 M

Answer

1.0 M

Question 13

Which of the following factors does NOT influence the rate of a chemical reaction?

Accepted Answer

Volume of the reaction vessel

Answer

Concentration of reactants

Answer

Nature of the catalyst

Answer

Temperature

Question 14

In an equilibrium reaction, why do the forward and reverse reactions proceed at equal rates?

Accepted Answer

To minimize changes in concentrations of reactants and products

Answer

To increase the concentrations of reactants

Answer

To alter the equilibrium position

Answer

To maximize the production of products

Question 15

Which reaction is an example of homogeneous equilibrium?

Accepted Answer

2NO(g) + O₂(g) ⇌ 2NO₂(g)

Answer

CaCO₃(s) ⇌ CaO(s) + CO₂(g)

Answer

PbCl₂(aq) + 2AgNO₃(aq) ⇌ Pb(NO₃)₂(aq) + 2AgCl(s)

Answer

C₂H₅OH(l) + O₂(g) ⇌ CH₃COOH(l) + H₂O(l)

Question 16

How do catalysts influence the activation energy of a chemical reaction?

Accepted Answer

Catalysts provide an alternative pathway for the reaction.

Answer

Catalysts increase the activation energy.

Answer

Catalysts are consumed during the reaction.

Question 17

A reaction has an activation energy of 100 kJ/mol. What is the approximate effect of increasing the temperature by 10 K on the rate of the reaction?

Accepted Answer

Rate increases by a factor of 2

Answer

Rate increases by a factor of 4

Answer

Rate decreases by a factor of 2

Question 18

The equilibrium constant for the reaction A + B ⇌ C is 10. What is the equilibrium concentration of C if the initial concentrations of A and B are both 1 M?

Accepted Answer

0.91 M

Answer

0.1 M

Answer

10 M

Answer

1 M

Question 19

What is the half-life of a first-order reaction?

Accepted Answer

Time required for the concentration of reactants to decrease by half

Answer

Time required for the rate of the reaction to decrease by half

Answer

Time required for the concentration of products to double

Question 20

Which of the following is a catalyst for the decomposition of hydrogen peroxide?

Accepted Answer

MnO2

Answer

NaCl

Answer

HCl

Answer

H2O

Question 21

Identify the reaction that exemplifies a first-order reaction.

Accepted Answer

A → B

Answer

A + B → C

Answer

A + B + C → D

Answer

A + 2B → C

Question 22

Define the equilibrium constant for a chemical reaction.

Accepted Answer

The ratio of the product concentrations to the reactant concentrations at equilibrium

Answer

The rate constant for the forward reaction

Question 23

Describe the half-life of a first-order reaction.

Accepted Answer

The time required for the reactant concentration to halve

Answer

The time required for the product concentration to double

Answer

The time required for the equilibrium constant to be reached

Question 24

Define a catalyst.

Accepted Answer

A substance that accelerates a reaction without being consumed

Answer

A substance that is produced in a reaction

Answer

A substance that slows down a reaction

Question 25

Explain the concept of activation energy in a chemical reaction.

Accepted Answer

The minimum energy required for the reactants to undergo a reaction

Answer

The maximum energy released during a reaction

Question 26

Identify the exothermic reaction.

Accepted Answer

A + B → C + heat

Answer

A + B → C + light

Answer

A + B → C + sound

Answer

A + B → C + electricity

Question 27

State Le Chatelier's principle.

Accepted Answer

When a stress is applied to a system at equilibrium, the system responds by shifting in a direction that alleviates the stress

Answer

When a stress is applied to a system at equilibrium, the system responds by shifting in a direction that intensifies the stress

Question 28

Describe the common ion effect.

Accepted Answer

The suppression of ionization of a weak acid or base when a common ion is introduced

Answer

The enhancement of ionization of a strong acid or base when a common ion is introduced

Answer

The absence of any effect on ionization when a common ion is introduced

Question 29

Which factor does not influence the rate of a chemical reaction?

Accepted Answer

Amount of product

Answer

Surface area of reactants

Answer

Concentration of reactants

Answer

Temperature

Question 30

At equilibrium, what is the value of the equilibrium constant?

Accepted Answer

Constant

Answer

Zero

Answer

Very large

Answer

Very small

Question 31

Which shift in conditions will shift the equilibrium of a reaction to the right in an exothermic process?

Accepted Answer

Increasing temperature

Answer

Adding more product

Answer

Decreasing temperature

Answer

Adding more catalyst

Question 32

What is the relationship between the equilibrium constant (K) and the Gibbs free energy change (ΔG°)?

Accepted Answer

ΔG° = -RTlnK

Answer

ΔG° = RTlnK

Answer

K = ΔG°/RT

Question 33

What is the standard enthalpy change of a reaction at equilibrium?

Accepted Answer

Zero

Answer

Negative

Answer

Depends on the temperature

Answer

Positive

Question 34

Which substance is a catalyst?

Accepted Answer

Enzymes

Answer

Inhibitors

Answer

Products

Answer

Reactants

Question 35

What is the Arrhenius equation?

Accepted Answer

k = Ae^(-Ea/RT)

Answer

Ea = Ae^(-k/RT)

Answer

R = Ae^(Ea/kT)

Answer

k = Ae^(Ea/RT)

Question 36

The activation energy of a reaction is the minimum energy required for the reaction to:

Accepted Answer

Form an activated complex

Answer

Break reactant bonds

Answer

Lower the energy of the reactants

Answer

Form product bonds

Question 37

Which of the following is the equilibrium constant expression for the reaction A + B <=> C?

Accepted Answer

[C]/[A][B]

Answer

[A][B]/[C]

Answer

[A] + [B]/[C]

Answer

[C] - [A]/[B]

Question 38

Which of the following changes will shift the equilibrium of the reaction A + B <=> C to the right?

Accepted Answer

Increasing the concentration of A

Answer

Adding a catalyst

Answer

Increasing the concentration of C

Answer

Decreasing the temperature

Question 39

Which of the following is a catalyst?

Accepted Answer

A substance that speeds up a reaction without being consumed

Answer

A substance that is produced in a reaction

Answer

A substance that slows down a reaction

Question 40

The rate law for a reaction is:

Accepted Answer

An expression that relates the rate of the reaction to the concentrations of the reactants

Answer

The change in concentration of the reactants over time

Answer

A constant that is specific to each reaction

Question 41

Which of the following is a homogeneous reaction?

Accepted Answer

A reaction in which all reactants and products are in the same phase

Answer

A reaction in which reactants and products are in different phases

Answer

A reaction that is catalyzed by a homogeneous catalyst

Question 42

Which of the following is a heterogeneous reaction?

Accepted Answer

A reaction in which reactants and products are in different phases

Answer

A reaction that is catalyzed by a heterogeneous catalyst

Answer

A reaction in which all reactants and products are in the same phase

Question 43

Which of the following is an example of a redox reaction?

Accepted Answer

A reaction in which electrons are transferred between atoms or ions

Answer

A reaction in which ions are formed

Answer

A reaction in which atoms are rearranged

Question 44

Which of the following is the oxidizing agent in the reaction Fe + CuSO4 -> FeSO4 + Cu?

Accepted Answer

CuSO4

Answer

Cu

Answer

FeSO4

Answer

Fe

Question 45

Which of the following factors **does NOT** affect the rate of a chemical reaction?

Accepted Answer

The type of glassware used

Answer

Concentration of reactants

Answer

Presence of a catalyst

Answer

Temperature

Question 46

The activation energy of a reaction is the minimum amount of energy required for the reactants to transform into the...

Accepted Answer

Activated complex

Answer

Reaction products

Answer

Intermediate product

Answer

Transition state

Question 47

A catalyst speeds up a reaction by lowering the...

Accepted Answer

Activation energy

Answer

Temperature

Answer

Equilibrium constant

Answer

Concentration of reactants

Question 48

The equilibrium constant, K_c, for a reaction represents the...

Accepted Answer

Ratio of the concentrations of products to reactants at equilibrium

Answer

Rate of the forward reaction

Answer

Rate of the reverse reaction

Question 49

A reaction with a large equilibrium constant (K_c >> 1) indicates that:

Accepted Answer

Products are predominantly formed at equilibrium

Answer

The reaction proceeds very slowly

Answer

Reactants are predominantly formed at equilibrium

Question 50

As a reaction progresses towards equilibrium, the rate of the...

Accepted Answer

Forward reaction decreases while the rate of the reverse reaction increases

Answer

Forward and reverse reaction rates remain constant

Answer

Forward reaction increases while the rate of the reverse reaction decreases

Question 51

In the Haber process for ammonia synthesis, increasing the temperature will:

Accepted Answer

Increase the rate of reaction but decrease the yield of ammonia

Answer

Decrease the rate of reaction and decrease the yield of ammonia

Answer

Increase the rate of reaction and increase the yield of ammonia

Question 52

A chemical reaction with a negative enthalpy change (ΔH < 0) is:

Accepted Answer

Exothermic, releasing heat

Answer

Neither exothermic nor endothermic

Answer

Endothermic, absorbing heat

Answer

Irreversible

Question 53

The rate law for a reaction is given by Rate = k[A]²[B]. What is the overall order of the reaction?

Accepted Answer

3

Answer

2

Answer

1

Question 54

Which of the following is NOT a factor that affects the rate of a chemical reaction?

Accepted Answer

The color of the reaction mixture

Answer

Temperature

Answer

Concentration of reactants

Answer

Presence of a catalyst

Question 55

What is the rate law expression for a reaction where the rate is directly proportional to the concentration of reactant A?

Accepted Answer

Rate = k[A]

Answer

Rate = k[A]^2

Answer

Rate = k[A][B]

Answer

Rate = k

Question 56

The following reaction is at equilibrium: A(g) + B(g) <=> C(g) + D(g). Which change will shift the equilibrium to the left, favouring the reactants?

Accepted Answer

Increasing the temperature if the forward reaction is endothermic

Answer

Adding more of reactant A

Answer

Decreasing the volume of the container

Answer

Adding a catalyst

Question 57

A weak acid (HA) has a Ka of 1 x 10^-5. What is the approximate pH of a 0.1 M solution of this acid?

Accepted Answer

3

Answer

4

Answer

6

Answer

5

Question 58

If the enthalpy change (ΔH) for a reaction is positive, what can you conclude about the reaction?

Accepted Answer

The reaction is endothermic, absorbing heat from the surroundings

Answer

The reaction is exothermic, releasing heat to the surroundings

Answer

The reaction is spontaneous

Answer

The reaction is non-spontaneous

Question 59

A reaction has a rate constant of 2.5 x 10^-3 s^-1 at 25 °C and 4.5 x 10^-2 s^-1 at 50 °C. What is the approximate activation energy (Ea) for this reaction?

Accepted Answer

75 kJ mol^-1

Answer

25 kJ mol^-1

Answer

50 kJ mol^-1

Answer

100 kJ mol^-1

Question 60

What is the overall order of a reaction with the following rate law: Rate = k[A]^2[B]^3?

Accepted Answer

5

Answer

6

Answer

2

Answer

3

Question 61

Which of the following pairs represents a conjugate acid-base pair?

Accepted Answer

NH3 and NH4+

Answer

H2O and OH-

Answer

CH3COOH and CH3COO-

Answer

HCl and NaCl

Question 62

Which of the following factors will NOT directly influence the rate of a chemical reaction?

Accepted Answer

The volume of the reaction vessel

Answer

The temperature of the reaction mixture

Answer

The presence of a catalyst

Answer

The concentration of reactants

Question 63

A reaction is found to have a rate constant of 1.5 x 10^-3 s^-1 at 25°C. What is the order of this reaction?

Accepted Answer

It is impossible to determine the order from the rate constant alone.

Answer

First order

Answer

Zero order

Question 64

The following reaction is at equilibrium: N2(g) + 3H2(g) ⇌ 2NH3(g). What will happen to the equilibrium position if the pressure is increased?

Accepted Answer

The equilibrium will shift to the right (towards product formation).

Answer

The equilibrium position will not change.

Answer

The equilibrium will shift to the left (towards reactant formation).